Vibration generator moving vibrator by magnetic field generated by coil and vibrator-mounted holder used in vibration-generator

ABSTRACT

A vibrator-mounted holder is attached to a casing of a vibration generator which moves a vibrator to generate a vibration when used. The vibrator-mounted holder includes a vibrator, a vibrator retention unit retaining the vibrator, a fixing unit fixed to a casing, and an arm. The vibrator includes a magnet having a plate shape parallel to a horizontal surface and a yoke arranged on the magnet. The arm connects the fixing unit to the vibrator retention unit, and supports the vibrator retention unit in a manner that the vibrator retention unit is displaceable with respect to the fixing unit. The yoke has a projecting portion which is projected downward and fixed to the vibrator retention unit. The arm is connected to a portion, at which the projecting portion is arranged, within the vibrator retention units.

This application is based on Japanese Patent Application No. 2013-8961filed with the Japan Patent Office on Jan. 22, 2013, the entire contentof which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a vibration generator, particularly toa vibration generator that moves a vibrator to generate a vibration bypassage of a current through a coil.

Description of the Related Art

As a vibration generator that moves a vibrator to generate vibration, avariety of vibration generators are used which has a structure in whicha vibrator including a magnet weight is supported by a chassis with aplate spring interposed. This vibration generator includes a coilarranged under the magnet. The coil is disposed opposite the magnet. Thevibrator moves while deforming the spring, in conjunction withgeneration of a magnetic field induced by an electric current whichflows through the coil.

Document 1 discloses a vibration generator having a structure in which avibration unit having the magnet is supported using a plate spring. Inthe vibration generator, one plate-like coil is disposed opposite themagnet of the vibration unit. One end of the plate spring is fixed to achassis with a screw. The other end of the plate spring is fixed to aweight of the vibration unit by caulking.

Document 2 discloses a vibration generating device, in which the magnetis attached to a movable block and the coil is wound around a rod-shapedyoke body disposed along the magnet. In the vibration generator, aspring unit supporting movable block, a rim unit of frame and the likeare integrally molded using resin material.

[Document 1] Japanese Patent Publication Laying-Open No. 2003-24871

[Document 2] Japanese Patent Publication Laying-Open No. 2010-94567

The vibration generator disclosed in Document 1 supports the vibratorusing a plate spring attached to the chassis. Therefore, the structureof an attachment unit for attaching the plate spring to the chassis iscomplicated. Specifically, in the vibration generator disclosed inDocument 1, the plate spring is attached to the chassis using a screw.Therefore, the steps of assembling the vibration generator arecomplicated, the number of parts increases, and the manufacturing costof the vibration generator increases.

Such a problem becomes more serious as the demand for smaller and athinner vibration generator increases. That is, as a vibration generatoris smaller, components of the vibration generator is also smaller;therefore, instead of screwing and clamping, an attaching method such asspot welding is necessary. Therefore, the structure of the attachmentunit for attaching components to each other becomes complicated. Forexample, when spot welding is performed to the attachment unit whichattaches the plate spring to the chassis, the attachment unit should bewelded in many positions so that high reliability of the vibrationgenerator can be achieved, and thus time and effort for manufactureincrease. It is because the portions which have undergone spot weldingbecome comparatively vulnerable to an impulsive force.

Furthermore, it is necessary for the vibration generator not to easilybreak down but have high reliability. In this vibration generator, inorder for the vibration generator to generate a big vibration with highefficiency and to have a thinner body, it is desirable to narrow a gapbetween the coil and the vibrator containing the magnet therein.However, when the gap is narrowed, there is a problem that the vibratoreasily comes into contact with the coil or the like when the vibratorvibrates in an up-and-down direction.

The present invention was made to solve the above problems, and anobject thereof is to provide a vibrator-mounted holder and a vibrationgenerator, which can be easily assembled, can be manufactured at lowcost, and have high reliability.

SUMMARY OF THE INVENTION

In order to achieve the above object, according to one aspect of thepresent invention, there is provided a vibrator-mounted holder attached,for use, to a chassis of a vibration generator configured to generate avibration by moving a vibrator, the vibrator-mounted holder including: avibrator including a magnet which has a plate shape parallel to ahorizontal surface, and a yoke arranged on the magnet; a vibratorretention unit retaining the vibrator; a fixing unit fixed to thechassis; and an arm connecting the vibration retention unit and thefixing unit to each other and supporting the vibrator retention unit ina manner that the vibrator retention unit is displaceable with respectto the fixing unit, wherein the yoke includes a projecting portion whichis projected down, the projecting portion is fixed to the vibratorretention unit, and the arm is connected to a portion, at which theprojecting portion is arranged, within the vibrator retention unit.

According to another aspect of the present invention, there is provideda vibration generator including a chassis; the vibrator-mounted holderdescribed above, the vibrator-mounted holder retaining the vibrator in amanner that the vibrator is displaceable with respect to the chassis;and a coil for generating a magnetic field for changing at least one ofa position and a posture of the vibrator with respect to the chassis,wherein the vibrator-mounted holder is attached to the chassis in astate where the arm switches to an extended state from a natural state.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating a vibration generator according to afirst embodiment of the present invention.

FIG. 2 is a sectional view taken on a line A-A of FIG. 1.

FIG. 3 is a perspective view illustrating a holder.

FIG. 4 is a cross-sectional view of a frame taken along a line B-B ofFIG. 1.

FIG. 5 is a sectional view of the frame taken along a line C-C of FIG.4.

FIG. 6 is a cross-sectional side view of a yoke taken along a line B-Bof FIG. 1.

FIG. 7 is a development view illustrating a substrate and a bottom plateaccording to one modification of the first embodiment.

FIG. 8 is a plan view illustrating the configuration of a vibrationgenerator according to a second embodiment.

FIG. 9 is a cross-sectional side view of the vibration generatoraccording to the second embodiment.

FIG. 10 is a bottom view illustrating a frame according to the secondembodiment.

FIG. 11 is a cross-sectional view taken along a line K-K of FIG. 10.

FIG. 12 is a perspective view illustrating a vibrator-mounted holder ofthe vibration generator.

FIG. 13 is an exploded perspective view of FIG. 12.

FIG. 14 is a cross-sectional perspective view illustrating an attachmentstructure by which a yoke is attached to the holder.

FIG. 15 is an explanatory view describing the configuration of theholder of the vibration generator according to the second embodiment.

FIG. 16 is an exploded perspective view illustrating a vibrator-mountedholder of a vibration generator according a first modification of thesecond embodiment.

FIG. 17 is a perspective view illustrating the vibrator-mounted holder.

FIG. 18 is a cross-sectional view of a frame used for a vibrationgenerator according to a second modification of the second embodiment.

FIG. 19 is a cross-sectional view of a frame used for a vibrationgenerator according to a third modification of the second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a vibration generator using a vibrator-mounted holderaccording to an exemplary embodiment of the present invention will bedescribed with reference to the drawings.

The vibration generator has a structure in which a vibrator holding amagnet is supported by a chassis in a manner capable of being able to bedisplaced relative to the chassis. A coil is arranged near the vibrator.The vibrator generates a magnetic field for changing at least one of aposition and a posture of the vibrator with respect to the chassis. Thevibration generator is a so-called linear type vibration generator whichgenerates a vibration force by causing the vibrator to reciprocateaccording to magnetization of the coil.

First Embodiment

FIG. 1 is a plan view illustrating a vibration generator according to afirst embodiment of the present invention. FIG. 2 is a sectional viewtaken on a line A-A of FIG. 1.

In FIG. 1, a holder 50 and the like, which are originally hidden behindan upper surface of a frame 20, are partially illustrated by a solidline for the purpose of easy understanding of a component layout in avibration generator 1.

In the following description, with respect to vibration generator 1,sometimes an X-axis direction of an coordinate in FIG. 1 is referred toas a crosswise direction (a positive direction of an X-axis is a rightdirection when viewed from an origin of the coordinate), and a Y-axisdirection is referred to as a front-back direction (a positive directionof a Y-axis is backward when viewed from the origin). Sometimes a Z-axisdirection (direction perpendicular to an XY-plane in FIG. 1) in FIG. 2is referred to as a vertical direction (a positive direction of a Z-axisis upward when viewed from the origin).

Entire Structure of Vibration Generator 1

As illustrated in FIG. 1, vibration generator 1 includes a double-sidedsubstrate (an example of a substrate) 10, frame (an example of achassis) 20, a bottom plate 30, a coil 40, and holder 50 roughly. In thepresent embodiment, holder 50 includes four pillar bodies (an example ofa fixing unit) 51 (51 a, 51 b, 51 c, 51 d), four arms 53 (53 a, 53 b, 53c, 53 d), and one vibrator retention unit (hereinafter, this may besimply referred to as a retention unit) 55. A vibrator 80 which isconfigured by a magnet 60 and a yoke 70 is held by retention unit 55.

Vibration generator 1 is formed into a substantially thin rectangularsolid body where a vertical size is relatively small, as a whole.Vibration generator 1 is a small object which is, for example, onlyabout 10 millimeters to 20 millimeters in each of outside dimensions inthe crosswise direction and the front-back direction. Vibrationgenerator 1 has a box-shaped external form where side surfaces on left,right, front, and back sides, and an upper surface are configured byframe 20 and a bottom surface is covered with double-sided substrate 10.

According to the present embodiment, frame 20 and yoke 70 are softmagnetic material, such as iron, for example.

Double-sided substrate 10 is a printed wiring board having patterns onboth surfaces thereof. Two terminals 11 and 12 are provided in a centerportion of an upper surface of double-sided substrate 10. Terminals 11and 12 are electrically connected to the pattern (not illustrated)provided on the bottom surface of double-sided substrate 10. A windingend of coil 40 is connected to terminals 11 and 12 using solder, and canbe electrically connected to coil 40 with the pattern on the bottomsurface of double-sided substrate 10. The method of connecting thewinding end of coil 40 is not limited to soldering, but coil 40 may beconnected to terminals 11 and 12 using a technique such as resistancewelding or laser welding.

Bottom plate 30 is a rectangular plate so that bottom plate 30 can coveralmost the entire upper surface of double-sided substrate 10. Bottomplate 30 and double-sided substrate 10 are fixed to each other, forexample, with an adhesive sheet, an adhesive, or the like. In otherwords, double-sided substrate 10 is connected to bottom plate 30 so asto be along bottom plate 30. An opening 31 is provided in a centerportion of bottom plate 30 so that two terminals 11 and 12 are exposedfrom above. Four connection units 33 (33 a, 33 b, 33 c, and 33 d) areformed at four sides of bottom plate 30. Each connection unit 33 isformed in a portion within the upper surface of double-sided substrate10 of bottom plate 30 and has an L-shaped section. Each connection unit33 is formed such that an outside surface of connection unit 33 comesinto contact with an inside surface of a side portion of frame 20.Bottom plate 30 is positioned at a longer distance from vibrator 80 thanfrom coil 40. That is, bottom plate 30 covers vibrator 80, coil 40, andthe like as well as frame 20.

In the present embodiment, bottom plate 30 is made of nonmagneticmaterials. Bottom plate 30 is made of nonmagnetic metallic materials,for example, nonmagnetic stainless steel. Bottom plate 30 may not belimited to an article made of metallic materials but be an article madeof resin, for example.

Frame 20 has a rectangular parallelepiped shape, in which a bottomportion is open, as a whole. Frame 20 is formed by performing areduction process on an iron plate. When viewed from above, corners(portions between sides) of frame 20 are connected with a R-surfaceportion interposed therebetween. As illustrated in FIG. 2, frame 20 isarranged in such a manner as to cover the upper surface of double-sidedsubstrate 10 from above double-sided substrate 10. Frame 20 is fixed tobottom plate 30 in such a manner that an inside surface at each sidewall thereof is in contact with a side surface of each connection unit33 of bottom plate 30 and thus each side wall is bonded or welded toeach connection unit 33. In other words, bottom plate 30 is attached toframe 20. Frame 20 may be fixed to bottom plate 30 in a manner of beingfitted into connection units 33 or in another manner.

Thus, because vibration generator 1 is structured in a manner to besurrounded by frame 20, vibration generator 1 is nearly unlikely to beinfluenced by the surrounding magnetic field, etc. Magnetic flux invibration generator 1 is difficult to leak outside, and thus themagnetic flux is difficult to influence external apparatus, circuits,and the like.

Since vibration generator 1 is surrounded by frame 20 and bottom plate30, in a box shape, the rigidity of vibration generator 1 itself ishigh. Therefore, vibration generator 1 can certainly generate avibration. Vibration generator 1 is easy to handle at the time ofattachment work, i.e., when vibration generator 1 is attached to anexternal instrument or the like.

Coil 40 is a plate-like air core coil which is formed by winding anelectrical wire, for example, and coil 40 has an elliptical form as awhole. That is, coil 40 is a thin coil where a size in a direction of awinding axis is smaller than a size in a direction orthogonal to thedirection of the winding axis. Coil 40 may be obtained by slicing ametallic foil-wound object, or by laminating sheet coils. Coil 40 mayhave a round shape or a polygonal shape, such as quadrangle shape in aplan view.

As illustrated in FIG. 2, coil 40 is arranged on the upper surface ofbottom plate 30 in a posture such that the direction of the winding axisis a vertical direction. As illustrated in FIG. 1, when viewed fromabove, coil 40 is disposed in a center portion of vibration generator 1and arranged in a face-to-face manner with respect to vibrator 80 asdescribed below. Coil 40 and bottom plate 30 are electrically insulatedfrom each other. Two winding ends of coil 40 are both wired to extendthrough opening 31 from the inner side of coil 40 and to reach the uppersurface side of double-sided substrate 10, and are connected toterminals 11 and 12.

Holder 50, magnet 60, and yoke 70 are integrally molded by insertmolding. That is, holder 50 and vibrator 80 are integrally molded. Inthe first embodiment, pillar body 51, arm 53, and retention unit 55 areintegrally molded using an elastic material (an example of the resin).For example, heat-resistant fluorine rubber or silicon rubber can beused as the elastic material. Holder 50 is made of the rubber, whichallows a heat resistance property of vibration generator 1 to beenhanced. The elastic material is not limited to the rubber, but variousmaterials may be used as the elastic material.

Structure of Holder 50 and Vibrator 80

FIG. 3 is a perspective view illustrating holder 50.

Holder 50 illustrated in FIG. 3 is in a state in which magnet 60 andyoke 70 are not attached to retention unit 55. That is, although holder50 is integrally molded with vibrator 80 which includes magnet 60 andyoke 70 in the present embodiment, as for this portion, vibrator 80 isnot illustrated but only holder 50 constituted by an elastic body isillustrated in FIG. 3.

Each pillar body 51 has a cylindrical shape where a height direction isthe vertical direction. A height of each pillar body 51 is slightlysmaller than the size of the inside space of frame 20 in the verticaldirection.

As illustrated in FIG. 1, four pillar bodies 51 are disposed at fourcorners of holder 50 when viewed from above. Each pillar body 51 isdisposed in the R-surface portion of the side surface of frame 20.

As illustrated in FIGS. 1 and 2, vibrator 80 has a plate shape parallelto the horizontal plane (an XY-plane in FIG. 1). Vibrator 80 is formedinto a substantially rectangular shape, in which each side is parallelto the front-back direction or the crosswise direction, when viewed fromabove.

As illustrated in FIG. 1, vibrator 80 is disposed in the central portionof holder 50, namely the central portion of vibration generator 1 whenviewed from above. As illustrated in FIG. 2, vibrator 80 is disposed insubstantially parallel to coil 40 while the surface of vibrator 80 isopposite the surface of coil 40.

Magnet 60 is a permanent magnet and has a thin rectangularparallelepiped shape. For example, in magnet 60, a bottom portion facingcoil 40 is magnetized into two poles such that an N pole and an S polemay be formed in front and back portions. Yoke 70 is a rectangularmagnetic plate when viewed from above and is attached in a manner tocover the upper surface of magnet 60. The upper surface of yoke 70 isdisposed to face the inside of the upper surface of frame 20. Yoke 70has handle portions 71 and 72 partially projected from left and rightsides thereof, respectively. Yoke 70 and magnet 60 are joined, forexample, by spot welding or with an adhesive to make up a piece ofvibrator 80. Vibrator 80 and holder 50 are integrally molded throughinsert-molding in the state where yoke 70 and magnet 60 are joined. Theupper surface of yoke 70 is provided with protruding portions 75 a and75 b.

As illustrated in FIG. 3, retention unit 55 has a quadratic frame shapehaving a substantially rectangular hole 55 a in which vibrator 80 isarranged. Here, retention unit 55 is provided with two bulging-outportions 55 b and 55 c which bulge leftward and rightward from bothsides of retention unit 55. As illustrated in FIG. 2, yoke 70 isdisposed together with magnet 60 in a manner that handle portions 71 and72 are buried in bulging-out portions 55 b and 55 c, respectively. Owingto this structure, vibrator 80 is difficult to be detached fromretention unit 55.

Four arms 53 connect corners of retention unit 55 to pillar bodies 51nearest to the corners, respectively. Each arm 53 is formed in the shapeof a beam extending in a left-and-right direction. As illustrated inFIG. 2, the size of each arm 53 in a widthwise direction(forward-and-rearward direction) is smaller than the size in alongitudinal direction (up-and-down direction). Since each arm 53 is anelastic body, each arm 53 easily bends in the forward-and-rearwarddirection. The relation between the size in the widthwise direction andthe size in the longitudinal direction of each arm 53 is not limited tothis. In each arm 53, the size in the widthwise direction may be equalto the size in the longitudinal direction or larger than the size in thelongitudinal direction.

Thus, each of four arms 53 is formed to more easily bend in a back andforth direction, which allows vibrator 80 to be displaced mainly in aback and forth direction with respect to pillar body 51. Namely,vibrator 80 is supported by arms 53 such that it can be displayed in adirection substantially parallel to a horizontal surface.

Four pillar bodies 51 of holder 50 are fixed to frame 20, whereby holder50 is attached to frame 20. Therefore, the basic structure of vibrationgenerator 1 is formed such that vibrator 80 is supported by holder 50,which is integrally molded separately from frame 20, while being able tobe displaced with respect to frame 20.

In vibration generator 1, coil 40 generates the magnetic field forcausing vibrator 80 to reciprocate with respect to frame 20. That is,when an electric current flows through coil 40, coil 40 is magnetizedand a magnetic field in the up-and-down direction is generated. When themagnetic field is generated, magnet 60 is influenced by this magneticfield, generating a repulsive/attractive force. According to thedirection of the magnetic field and the arrangement of the magneticpoles of the magnet 60, a force of displacing vibrator 80 forward orrearward acts on vibrator 80. Therefore, vibrator 80 is displaced toeither the forward direction or the rearward direction, letting each arm53 bend flexibly. Therefore, when an alternating current is transmittedto coil 40, vibrator 80 performs reciprocating linear motion in theforward-and-rearward direction with respect to frame 20 when viewed fromabove according to the alternating current. Thereby, vibration generator1 generates vibration force.

When the current value of the alternating current decreases, themagnetic field becomes weak, or the magnetic field is lost, vibrator 80tries to return to the center portion of vibration generator 1 whenviewed from above, due to restoring force of arm 53. At this time, sincearm 53 is an elastic body, the energy consumed by arm 53 iscomparatively large. Therefore, the vibration is promptly attenuated.

In this embodiment, since bottom plate 30 is made of nonmagneticmaterials, the magnetic attractive force of magnet 60 is not generatedbetween vibrator 80 and bottom plate 30. Vibrator 80 is smoothly andefficiently displaced according to the magnetic field generated by coil40. Therefore, vibration generator 1 can be thinned and can be properlyoperated.

Attachment Structure for Attaching Holder 50 to Frame 20

In the first embodiment, pillar body 51 engages an engaging unit 21 (21a, 21 b, 21 c, and 21 d) provided in frame 20, thereby attaching pillarbody 51 to frame 20. Therefore, holder 50 is configured to be able to beeasily attached to frame 20.

FIG. 4 is a sectional view of frame 20 taken on a line B-B of FIG. 1.FIG. 5 is a sectional view of frame 20 taken on a line C-C of FIG. 4.

In the first embodiment, as illustrated in FIG. 5, engaging units 21 areprovided in the corner portions of frame 20 when viewed from above. Eachof four engaging units 21 includes two claws 22 and 23, namely, a firstclaw 22 (22 a, 22 b, 22 c, and 22 d) and a second claw 23 (23 a, 23 b,23 c, and 23 d).

As illustrated in FIG. 4, a U-shape notch is partially provided in theside surface of frame 20, and an interior portion of the notch ispressed into the inside of frame 20, thereby forming each of claws 22and 23 of engaging unit 21. Accordingly, claws 22 and 23 and frame 20are integrally molded. Each of claws 22 and 23 is formed in the abovemanner to partially provide a gap 25 (25 a, 25 b, 25 c, and 25 d) in theside surface of frame 20.

In the first embodiment, claws 22 and 23 are formed into the shapecorresponding to the shape of pillar body 51. That is, because pillarbody 51 has the columnar shape, claws 22 and 23 are formed into theshape along a side circumferential surface of pillar body 51. Asillustrated in FIG. 5, when viewed from above, each engaging unit 21 isformed such that at least a semicircle of the outer circumferencesurface of pillar body 51 disposed in engaging unit 21 is surrounded byclaws 22 and 23 and the R-surface portion between the side surfaces offrame 20.

In the case that holder 50 is disposed in frame 20, four pillar bodies51 are fitted in four engaging units 21. Therefore, each pillar body 51is held between claws 22 and 23 of engaging unit 21. In other words, ineach pillar body 51, the side circumferential surface is gripped byclaws 22 and 23 of engaging unit 21. Pillar body 51 and engaging unit 21engage each other to fix pillar body 51 to frame 20, thereby attachingholder 50 to frame 20.

Each of claws 22 and 23 is fixed to corresponding pillar body 51 in acaulking manner in a state in which pillar bodies 51 are fitted inengaging units 21, respectively. As illustrated by an arrow of FIG. 5,for example, a first claw 22 d is pushed forward (lower side in FIG. 5)to be inserted into, for example, engaging unit 21 d, and a second claw23 d is pushed rightward (right side in FIG. 5) to be inserted intoengaging unit 21 d. Thus, by caulking of claws 22 and 23, claws 22 and23 bite into respective pillar bodies 51, which allows pillar bodies 51to be more firmly fixed to frame 20.

In the vibration generator in the background art, the vibrator issupported using the plate spring attached to the chassis. For example,in the vibration generator in which the plate spring is attached to thechassis using the screw, unfortunately the structure of the portion inwhich the plate spring is attached onto the chassis side becomescomplicated. Therefore, the assembly man-hour of the vibration generatorincreases, and the number of components also increases, which increasesthe production cost of the vibration generator. The problem becomes moreprominent with increasing demand for the downsizing and the low profileof the vibration generator. That is, because the downsizing of thecomponent advances with the downsizing of the vibration generator, it isnecessary to adopt attachment methods, such as the spot welding, insteadof the screw clamp or caulking, and the structure of the attachmentportion between the components becomes complicated. For example, in thecase that the spot welding is performed to the attachment portion of theplate spring and the chassis, the region where the spot welding isperformed becomes brittle against the impact force. Therefore, it isnecessary to perform the spot welding at many points in order tomaintain high reliability of the vibration generator, and sometimes ittakes a lot of trouble with the production. The problem with the methodfor joining the spring unit and the chassis is not originally generatedin the vibration generating device in the background art that has thestructure in which the spring unit and the frame are integrally molded.However, in this case, unfortunately the material used for the chassisis restricted to a material, which can be molded while being integralwith the spring unit.

On the other hand, in the first embodiment, holder 50 including pillarbody 51 is integrally molded, and pillar body 51 is fitted in engagingunit 21 to attach holder 50 to frame 20. Holder 50 can easily beattached to frame 20, and the number of components is suppressed to alow level, so that the production cost of vibration generator 1 can bereduced. Because each holder 50 and frame 20 is integrally formed, theattachment portion of holder 50 and frame 20 does not become brittle.Accordingly, the reliability of vibration generator 1 can be enhancedagainst the impact. It is not necessary to attach holder 50 to frame 20using other members, such as the screw, so that the downsizing, lowprofile, weight reduction of vibration generator 1 can be implemented.

In the structure of the background art in which the spring unitsupporting the vibrator and the chassis are integrally molded usingresin, unfortunately it is necessary that the spring unit and thechassis be made of the same material for the viewpoint of materialselection. However, in the first embodiment, the number of componentsdecreases because holder 50 and frame 20 are constructed by differentmembers. While holder 50 and frame 20 have the simple structures thatcan easily be assembled, the material for frame 20 can properly beselected. Accordingly, frame 20 can be configured to exert its functionwithout separately providing a member that acts as a magnetic circuit ora magnetic shield.

In holder 50, pillar body 51, arm 53, and vibrator retention unit 55 areintegrally molded using the elastic material. Accordingly, the number ofcomponents decreases, and holder 50 can easily be produced. In the firstembodiment, magnet 60 and yoke 70 are formed by the insert moldingtogether with holder 50. Accordingly, holder 50 can easily beconstructed while retaining vibrator 80, and a production process ofvibration generator 1 can be simplified.

Engaging unit 21 and frame 20 are integrally formed such that claws 22and 23 are formed while the notch is partially provided in the sidesurface of frame 20. Accordingly, the number of components can decreaseto reduce the production cost.

In the attachment structure of holder 50 to frame 20, columnar pillarbody 51 is gripped by two claws 22 and 23. Accordingly, while thestructure of vibration generator 1 is simplified, pillar body 51 issurely positioned in frame 20, and accuracy of the attachment of holder50 to frame 20 can be enhanced. Because of the structure in which claws22 and 23 are caulked with respect to pillar body 51, holder 50 isstrongly attached to frame 20.

The attachment structure for attaching vibrator 80 to holder 50, i.e.,the attachment structure for attaching magnet 60 and yoke 70 to holder50 is not limited to an article prepared through insert molding. Forexample, magnet 60 and yoke 70 which are mutually joined through weldingor the like are incorporated into holder 50, and bonded. Alternatively,holder 50 and yoke 70 may be integrally formed and thereafter magnet 60may be attached to yoke 70.

Structure of Yoke 70

Vibrator 80 moves in response to the influence of the magnetic fieldgenerated by the coil arranged under vibrator 80. Vibrator 80 isdisplaced in an up-and-down direction, or tilted from a horizontalsurface. (In this sense, the movement of vibrator 80 is not performedstrictly within the level surface. However, the quantity of thedisplacement of vibrator 80 in the up-and-down direction or the quantityof the change in the posture is comparatively small. Therefore,hereinafter the movement of vibrator 80 may be expressed as “movelaterally” in a macroscopic sense.) In the case where force is appliedto vibration generator 1 from the outside, vibrator 80 may be displacedto frame 20 in the up-and-down direction. Vibration generator 1 has athin structure and an interval between frame 20 and the upper surface ofvibrator 80 is comparatively narrow. Therefore, when vibrator 80 isdisplaced with respect to frame 20 in the up-and-down direction ortilted to frame 20 in this way, the upper surface of vibrator 80 maycome into contact with the inside of the upper surface of frame 20.

In the present embodiment, when vibrator 80 is displaced in theup-and-down direction or tilted to frame 20, two protruding portions 75a and 75 b within the upper surface of yoke 70 may come into contactwith frame 20.

As illustrated FIG. 1, protruding portions 75 a and 75 b are providedsuch that they may protrude toward the inside of the upper surface offrame 20 from the upper surface of yoke 70. Protruding portions 75 a and75 b are provided in two positions which are mutually symmetrical toeach other with respect to a plane (plane which is parallel to a ZXplane), which is perpendicular to the forward-and-rearward direction asa movement direction of vibrator 80, the plane passing through thecenter of vibrator 80. Protruding portions 75 a and 75 b are located intwo positions on a plane which is parallel to a YZ plane and passes thecenter of vibrator 80. That is, in the present embodiment, protrudingportion 75 a is provided in a rear side at a left-and-right directioncenter portion within the upper surface of vibrator 80. Protrudingportion 75 b is provided in a front side at the left-and-right directioncenter portion within the upper surface of vibrator 80, i.e., in aposition symmetrical with protruding portion 75 a.

FIG. 6 is a cross-sectional side view of yoke 70, taken along a line B-Bof FIG. 1.

As illustrated in FIG. 6, in the present embodiment, each of protrudingportions 75 a and 75 b has a curved surface shape which is convex upward(right side in FIG. 6). In other words, when each of protruding portions75 a and 75 b has a convex curved surface which is convex towards theinside of the upper surface of frame 20. The surface shape of each ofprotruding portions 75 a and 75 b is, for example, a substantiallyspherical shape (i.e., an approximately arc shape in the sectionillustrated in FIG. 6). Each of protruding portions 75 a and 75 b isformed through press working or steel metal working such that they arepressed to protrude upward from plate-like yoke 70. That is, each ofprotruding portions 75 a and 75 b is integrally formed with otherportions of yoke 70. Each of protruding portions 75 a and 75 b is notlimited to this structure. For example, each of protruding portions 75 aand 75 b may be provided in a manner that members which are separatedfrom the body of yoke 70 are attached to the upper surface of yoke 70.Each of protruding portions 75 a and 75 b may be formed by applyingliquid members (for example, epoxy-based resin material, molten metal,etc.) to the upper surface of yoke 70, and curing or solidifying theliquid members.

Thus, since protruding portions 75 a and 75 b are provided within theupper surface of yoke 70 in the present embodiment, even when vibrator80 approaches frame 20, protruding portions 75 a and 75 b come intocontact with frame 20 first. Since the portion that comes into contactwith frame 20 is restricted to protruding portions 75 a and 75 b, thearea in contact with frame 20 is also restricted. Therefore, whenprotruding portions 75 a and 75 b among portions of vibrator 80 comeinto contact with frame 20, a frictional force which acts on vibrator 80is decreased, reducing the influence on the operation of vibrator 80.Vibration generator 1 which can properly operate can be thinned. Sincethe frictional force which acts on vibrator 80 can be reduced, powerconsumption of vibration generator 1 can be reduced. It is possible toprevent inhibition of the operation of vibrator 80 attributable to anevent that vibrator 80 comes into contact with frame 20, and vibrator 80can be operated smoothly.

Protruding portions 75 a and 75 b are symmetrically arranged withrespect to the movement direction (vibrating direction) of vibrator 80.Therefore, when vibrator 80 comes into contact with frame 20 at the timeof vibration of vibrator 80, protruding portions 75 a and 75 b certainlycome into contact with frame 20, and other portions of vibrator 80 aredifficult to come into contact with frame 20. Therefore, the influenceon the operation of vibrator 80 by an event that vibrator 80 comes intocontact with frame 20 can be certainly reduced.

Since each of protruding portions 75 a and 75 b has a spherical surfaceshape which is convex toward the inside of the upper surface of frame20, each of protruding portions 75 a and 75 b and frame 70 comes intopoint contact with each other. Therefore, the frictional force whichacts on vibrator 80 can be certainly decreased, and thus vibrator 80 canbe reliably operated.

Modification of First Embodiment

Vibration generator 1 may include a substrate and a bottom plate havinga structure different from double-sided substrate 10 and bottom plate 30instead of double-sided substrate 10 and bottom plate 30.

FIG. 7 is a development view illustrating a substrate 210 and a bottomplate 230 according to one modification of the first embodiment.

Substrate 210 is a Flexible Printed Circuit board (FPC), and is arrangedin such a manner that bottom plate 230 is inserted in substrate 210. Inother words, substrate 210 is arranged to partially cover both surfacesof bottom plate 230. In FIG. 7, substrate 210 is expanded in the form ofplane.

Bottom plate 230 has a flat plate shape. Bottom plate 230 is insertedfrom the bottom side of frame 20, and fixed to frame 20. Referring toFIG. 7, a notch portion 235 is provided in a portion (an example of aportion of an edge portion) located in an upper portion among edgeportions of bottom plate 230. Because of this structure, the inside andthe outside of vibration generator 1 communicate with each other throughthe notch portion 235 in a state where bottom plate 230 is fixed toframe 20.

Bottom plate 230 is made of nonmagnetic materials, for example,nonmagnetic stainless steel. Since vibration generator 1 is surroundedby frame 20 and bottom plate 230 which are metallic materials, vibrationgenerator 1 can be more easily handled, and the durability of vibrationgenerator 1 is raised.

Substrate 210 has an upper surface portion 216 arranged along the uppersurface of bottom plate 230 and a bottom surface portion 217 arrangedalong the bottom surface of bottom plate 230. A portion between uppersurface portion 216 and bottom surface portion 217 serves as a foldedportion 218. Upper surface portion 216 is arranged to be interposedbetween a coil 40 and bottom plate 230. In folded portion 218 located innotch portion 235, substrate 210 is folded such that bottom surfaceportion 217 of substrate 210 is along the bottom surface of bottom plate230. Substrate 210 is bonded and fixed to bottom plate 230 etc., forexample.

As illustrated in FIG. 7, two pads 211 and 212 are provided in uppersurface portion 216 of substrate 210, and two pads 211 a and 212 a areprovided in bottom surface portion 217 of substrate 210. Pads 211 and211 a are connected to each other with a wiring pattern so as to be atthe same electrical potential and pads 212 and 212 a are connected toeach other with a wiring pattern so as to be at the same electricalpotential. A winding end of coil 40 is connected to pads 211 and 212provided in upper surface portion 216. Pads 211 a and 212 a provided inbottom surface portion 217 serve as electrodes when vibration generator201 is mounted on a circuit or the like.

Thus, with the use of substrate 210 which is an FPC, as compared withthe case where a double-sided substrate is used, the size of vibrationgenerator 1 in the up-and-down direction can be reduced. Furthermore,the shape of bottom plate 230 can be simplified.

Since notch portion 235 is provided in bottom plate 230, substrate 210is not projected outside from the chassis so that substrate 210 can becertainly protected.

Since bottom plate 230 is made of nonmagnetic materials, even when theinterval between vibrator 280 and bottom plate 230 is narrow like in thefirst embodiment, operation of vibrator 280 is not inhibited. Therefore,it is possible to provide thin vibration generator 1 with highdurability, thin vibration generator 1 being covered by bottom plate 230at the bottom thereof.

Second Embodiment

In a second embodiment, an attachment structure for attaching a holderto a frame and an attachment structure for attaching a vibrator,especially a portion related to a yoke, to the holder are different fromthe first embodiment and the modification thereof.

FIG. 8 is a plan view illustrating the configuration of a vibrationgenerator 301 according to the second embodiment. FIG. 9 is across-sectional side view of vibration generator 301 according to thesecond embodiment.

In FIG. 8, a holder 350 hidden under an upper surface of a frame 520,and the like are illustrated partially in a solid like in FIG. 1. Inaddition, in FIG. 8, illustration of a flexible printed circuit board isomitted. The structure of the portion which is omitted in illustrationis substantially the same as those of the first embodiment and themodification thereof.

Vibration generator 301 differs in the following point from vibrationgenerator 1 of the first embodiment or the modification thereof. Thatis, vibration generator 301 includes holder 350 instead of holder 50.Vibration generator 301 includes frame 520 instead of frame 20. Otherstructures of vibration generator 301 are the same as those of vibrationgenerator 1. As a bottom plate, bottom plate 230 illustrated in FIG. 7is used. As the substrate, a substrate 310 which is an FPC likesubstrate 210 and has an upper surface portion 316 and a bottom surfaceportion 317 is used.

Holder 350 is a vibrator-mounted holder retaining a vibrator 380 and isattached to a frame 520. Holder 350 is configured such that a movementdirection of vibrator 380 is a left-and-right direction (X-axisdirection of FIG. 8).

In the second embodiment, the attachment structure for attaching holder350 to frame 520 is configured as follows. That is, as illustrated inFIG. 8, holder 350 has four pillar bodies (an example of a fixing unit)351 (351 a, 351 b, 351 c, and 351 d). Pillar bodies 351 are provided inpositions corresponding to pillar bodies 51 in holder 50. As pillarbodies 351 are fixed to frame 520 in a manner described below, holder350 is supported by frame 520.

Holes 352 (352 a, 352 b, 352 c, and 352 d) are provided in pillar bodies351 of holder 350, respectively. Each hole 352 is formed to penetratethrough the corresponding pillar body 351, i.e., from the upper surfaceto the lower surface. Each hole 352 has a cylindrical shape. Each hole352 is formed such that an up-and-down direction, which is perpendicularto a left-and-right direction, i.e. a movement direction, of a vibratoris a depth direction. In other words, each hole 352 is formed to extendalong the up-and-down direction which is almost perpendicular to aplate-like vibrator which is almost substantially horizontally arranged.

FIG. 10 is a bottom view illustrating frame 520 according to the secondembodiment. FIG. 11 is a cross-sectional view taken along a line K-K ofFIG. 10.

As illustrated FIG. 10, poles 521 (521 a, 521 b, 521 c, and 521 d) arearranged at four corners of frame 520, respectively in a bottom view.Each of four poles 521 is a pin having a cylindrical shape. Poles 521are arranged in positions corresponding to four holes 352 in holder 350,respectively. As illustrated in FIG. 11, each pole 521 is arranged suchthat a longitudinal direction thereof becomes the up-and-down direction,i.e., a direction which is perpendicular to the movement direction ofthe vibrator. Each pole 521 is erected on frame 520 such that upper endsof poles 521 are press-fitted into press-fitting holes 522 (522 a, 522b, 522 c, and 522 d) formed in a top panel (bottom side in FIG. 11) ofthe body of frame 520, and lower ends of poles 521 protrude downwardfrom the lower surface of the top panel. Each pole 521 protrudes fromthe top panel of the body of frame 520 by a length which is shorter thanthe size of pillar bodies 351 in the up-and-down direction. Althougheach pole 521 is made of, but not limited to, metallic materials, suchas iron. For example, each pole 521 may be molded using resin.

Holder 350 is attached to frame 520 in such a manner that poles 521 a,521 b, 521 c, and 521 d are fitted into holes 352, respectively from theupper side. In the state where holder 350 has been arranged on frame520, bottom plate 230 is arranged on the underside of holder 350. Asholder 350 is prevented from being pulled out and being separated frompoles 521 in this way, holder 350 remains attached to frame 520. Holder350 is attached to frame 520 in the state where the magnet and the likeare attached beforehand.

In the second embodiment, holder 350 is attached to frame 520 in such amanner that pillar bodies 351 are fitted into poles 521 in this way.Therefore, it is not necessary to provide a notch portion for holdingpillar bodies 351 in a side surface of frame 520 unlike the firstembodiment. Since it is not necessary to provide holes in frame 520,vibration generator 501 is surrounded with frame 520 and bottom plate230 to have a sealed structure. Therefore, intrusion of foreignsubstances, such as dirt and dust into vibration generator 501 can beprevented, and the reliability of vibration generator 501 can be raised.Furthermore, a caulking step, etc. for pillar bodies 351 which arecomparatively complicated are not necessary, and holder 350 can beeasily attached to frame 520 by fitting poles 521 into holes 352.

An outside circumferential surface of each pillar body 351 is in contactwith and along an inside circumferential surface of frame 520 in thestate where holder 350 is attached to frame 520. That is, each pillarbody 351 is formed in the shape which is along a round-chamfered surfaceportion and planar surface portions at both sides of the round-chamferedsurface portion among portions of the inside circumferential surface offrame 520. Thereby, pillar bodies 351 are in contact with the insidecircumferential surface of frame 520 in a relatively wide range in thestate where holder 350 is attached to frame 520. Therefore, pillarbodies 351 are certainly retained so that the positions or posturesthereof with respect to frame 520 may not change.

Holder 350 has vibrator 380 and arms 353 (353 a, 353 b, 353 c, and 353d) which connect vibrator 380 to respective pillar bodies 351, besidespillar bodies 351 arranged in positions corresponding to respectivepoles 521 as described above. In holder 350, these portions areintegrally molded using resin.

FIG. 12 is a perspective view illustrating a vibrator-mounted holder ofvibration generator 301. FIG. 13 is an exploded perspective view of FIG.12.

As illustrated in FIG. 12, vibrator 380 includes magnet 60, a yoke 370,and a weight 381. Weight 381 is formed to surround side portions ofmagnet 60. Yoke 370 is attached to the upper surfaces of magnet 60 andweight 381. Yoke 370 has holes 371 a and 371 b formed in left and rightsides of the yoke. Protrusions 381 a and 381 b formed to protrude upwardfrom the upper surface of weight 381 are fitted into holes 371 a and 371b.

Each arm 353 is formed so that a forward-and-rearward direction becomesa longitudinal direction. That is, arms 353 a and 353 b are providedbetween pillar bodies 351 a and 351 b and a right end portion ofvibrator 380, respectively. On the other hand, arms 353 c and 353 d areprovided between pillar bodies 351 c and 351 d and a left end portion ofvibrator 380. As illustrated in FIG. 13, left and right side portions ofweight 381 are retained by retention units 355 a and 355 b made ofresin. Retention units 355 a and 355 b are formed so that side portionsof weight 381 may be pinched between front and rear portions ofretention units 355 a and 355 b, respectively. Each arm 353 is connectedto retention units 355 a and 355 b in the side of vibrator 380.

In the second embodiment, left and right ends of yoke 370 are providedwith projected portions 372 a and 372 b which are projected downward.Side edge portions of yoke 370 are bent down at about 90° to formprojected portions 372 a and 372 b, respectively. Recessed portions 357a and 357 b which are recessed from the upper surface of retention units355 a and 355 a are formed in retention units 355 a and 355 b,respectively. Recessed portions 357 a and 357 b are formed in positionscorresponding to projected portions 372 a and 372 b.

Holder 350 and vibrator 380 are integrally molded when holder 350 ismolded. That is, in the second embodiment, pillar body 351, 353, andretention unit 355 are integrally molded with yoke 370 using resin.Thereby, holder 350 and vibrator 380 can be molded in the state whereprojected portions 372 a and 372 b are certainly fitted into recessedportions 357 a and 357 b. Yoke 370 may be fixed to holder 350 which ismolded beforehand through a method such as bonding.

FIG. 14 is a cross-sectional perspective view illustrating an attachmentstructure for attaching yoke 370 to holder 350.

As illustrated in FIG. 14, almost entire parts of projected portions 372a and 372 b except for boundary portions at which they are bent areburied in recessed portions 357 a and 357 b. In other words, retentionunits 355 a and 355 b are formed to encase almost the entire part ofprojected portion 372 a and 372 b.

FIG. 15 is an explanatory view describing the configuration of holder350 of vibration generator 301 according to the second embodiment.

In FIG. 15, one arm 353 c in the bottom view of vibration generator 301is illustrated in an expanded manner.

In holder 350 of a natural state (for example, state where holder 350 isnot attached to frame 520), a distance between pillar body 351 a andpillar body 351 b is smaller than a distance between the medial axes ofpoles 521 a and 521 b. In addition, in the natural state, a distancebetween pillar body 351 c and pillar body 351 d is smaller than adistance between the medial axes of poles 521 c and 521 d. Therefore, asindicated by an arrow Q in FIG. 15, when holder 350 is attached to frame520, each arm 353 is extended a little longer in the longitudinaldirection than that in the natural state. Namely, each arm 353 switchesto the state where it is elastically deformed to be extended from thenatural state where holder 350 is attached to frame 520.

In holder 350 mounted with vibrator 380, since each arm 353 is attachedto frame 520 in the state where each arm 353 is extended from thenatural state, holder 350 experiences tension due to restoring force offour arms 353. A spring force F generated due to each arm 353 is a valueobtained by multiplying a displacement x by a spring constant k of arm353. Since the vectors of restoring forces differ, vibration generator301 is stable as vibration generator 301 is pulled by arms 353, and isin the state where there is no redundant space. Thereby, when a magneticattractive force acts on vibrator 380, vibrations can be promptlygenerated by vibration generator 301 in response to the displacement ofvibrator 380, and thus the response for vibration generation is raised.

Here, suppose a case where projected portions 372 a and 372 b are notformed in yoke but the yoke is just placed on retention units 355 a and355 b. In this case, if arm 353 is extended when holder 350 is attachedto frame 520, the position of vibrator 380 may be shifted to the coilside (lower side). This problem occurs due to a difference in anextension amount of each of retention units 355 a and 355 b between anupper portion (side to which yoke 370 is bonded) and a lower portion(side to which yoke 370 is not bonded) of each of retention units 355 aand 355 b to which arms 353 are connected.

On the other hand, in the second embodiment, as described above, asprojected portions 372 a and 372 b are arranged to be buried inretention units 355 a and 355 b, and each arm 353 is connected to thisportion. In this way, by bending the end of yoke 370 and fixing theperiphery of the end of yoke 370 with rubber, the fixed state at theupper portion and the fixed state at the lower portion of each ofretention units 355 a and 355 b are the same. In this way, if the fixedstate is almost the same between the upper portion and lower portion ofeach of retention units 355 a and 355 b, extension rates thereof becomealmost equal. Accordingly, even though arms 353 are pulled to beattached to frame 520, upper and lower positions of vibrator 380 do notchange. For this reason, vibrator 380 and coil 340 are not likely tocome into contact with each other. Therefore, the gap between vibrator380 and coil 340 and the size of vibration generator 301 in theup-and-down direction can be reduced, with vibrator 380 being certainlymaintained in the movable state. Since the gap between vibrator 380 andcoil 340 can be reduced, the force acting between vibrator 380 and coil340 can be increased, and a big vibration can be obtained.

Aside from this, since the second embodiment has features similar tothose of the first embodiment, effects similar to those described abovecan be obtained.

Modification of Second Embodiment

FIG. 16 is an exploded perspective view illustrating a vibrator-mountedholder of a vibration generator according a first modification of thesecond embodiment. FIG. 17 is a perspective view illustrating thevibrator-mounted holder.

As illustrated in FIG. 16, in the present modification, a vibrator 1380and a holder 1350 which are thick in an up-and-down direction and whichare slightly large are used. In the present modification, holder 1350 isdivided into four pieces and each piece includes a pillar body 1351(1351 a to 1351 d), an arm 1353 (1353 a to 1353 d) constituted by twobeams, and a retention unit 1355 (1355 a to 1355 d). Four retentionunits 1355 retain a weight 1381 with an end portion of a weight 1381interposed between two retention units 1355 adjacent to each other. Forexample, as for retention unit 1355 a, weight 1381 is retained such thatweight 1381 is interposed between retention unit 1355 a and retentionunit 1355 b and between retention unit 1355 a and retention unit 1355 d.

Magnet 60 is arranged in a center portion of weight 1381. Even in thepresent modification, a yoke 1370 is arranged on magnet 60. End portionsof yoke 1370 are bend down to form projected portions 1372 (1372 a to1372 d), end portions corresponding to respective retention units 1355.Recessed portions 1357 (1357 a to 1357 d) are formed in retention units1355, respectively so that projected portions 1372 may be buriedtherein. As illustrated in FIG. 17, yoke 1370 is attached to holder 1350in the state where each projected portion 1372 is arranged in eachretention unit 1355 in a manner that the almost entire part of eachprojected portion 1372 is buried in corresponding recessed portion 1357.In other words, retention units 1355 are formed to encase projectedportions 1372, respectively. In addition, holder 1350 is integrallymolded to encase each projected portion 1372, and thus each projectedportion 1372 can be more certainly retained by each retention unit 1355.

This holder 1350 is attached to a chassis of a vibration generator whenarm 1353 is switched to an extended state from a natural state. In thiscase, even in the present modification, since arms 1353 are in contactwith retention units 1355 into which projected portions 1372 are sunk,vibrator 1380 is not displaced in the up-and-down direction in responseto extension of arms 1353. Therefore, the same effect as that describedabove can be obtained.

In the second embodiment, the attachment structure for attaching thepole to frame is not limited to the press-fitting structure describedabove. The pole may be attached to the frame through welding, bonding, acoupling method using a screw, or the like. Each pole may be providedwith a flange which comes into contact with the body of frame.

FIG. 18 is a cross-sectional view of a frame 620 used for a vibrationgenerator according to a second modification of the second embodiment.

FIG. 18 is a view illustrating a section corresponding to the sectionillustrated in FIG. 11.

As illustrated in FIG. 18, the basic structure of frame 620 is the sameas that of frame 520 described above. Frame 620 differs from frame 520in the point that frame 620 includes poles (an example of the protrudingportions) 621 (621 a and 621 d) instead of poles 521 and step portions623 (623 a and 623 d). The step portions 623 are provided in portions,at which poles 621 are arranged, within the upper surface of the body(lower side portion in FIG. 18), and are one step lower than otherportions. In FIG. 18, only two poles 621 and two step portions 623 areillustrated. However, poles 621 and step portions 623 may be present inthe number of four each like in frame 520.

As illustrated in FIG. 18, an upper end portion of each pole 621 isprovided with a flange-like head 622 (622 a and 622 d) having a diameterlarger than that of the trunk of each pole 621. Head 622 is configuredsuch that the height in an up-and-down direction is smaller than theheight of the step from the upper surface of frame 520 to the uppersurface of step portion 623.

Each pole 621 is attached to frame 620 such that each pole 621 isinserted, from the upper side to the lower side, into a hole (notillustrated) formed in each step portion 623 and head 622 is caught bystep portion 623. Each pole 621 is fixed to frame 620 in a manner thatthe periphery of head 622 is welded to step portion 623. With theprovision of head 622, the size of each pole 621 which protrudes downcan be managed with high precision, the vibration generator having aprecise structure can be easily manufactured.

In this way, attachment strength of pole 621 to frame 620 can beenhanced by fixing pole 621 to frame 620 by welding. Therefore, thedurability of the attachment structure of pole 621 with respect tovibration etc. can be raised. Since frame 620 is provided with stepportion 623, it is possible to prevent a welded portion from beingprojected down from the upper surface of frame 620.

Alternatively, frame 620 may not be provided with step portion 623. Pole621 may not be provided with head 622.

FIG. 19 is a cross-sectional view of a frame 525 used for a vibrationgenerator according to a third modification of the second embodiment.

FIG. 19 is a view illustrating a section corresponding to the sectionillustrated in FIG. 11.

As illustrated in FIG. 19, the basic structure of frame 525 is the sameas that of frame 520 described above. Frame 525 differs from frame 520in a point that frame 525 includes poles 526 (526 a and 526 d) providedwith flanges 527 (527 a and 527 d). In FIG. 19, as for poles 526 andflanges 527, only poles 526 a and 526 d and flanges 527 a and 527 d areillustrated. However, poles 526 and flanges 527 may be present in thenumber of four each like in frame 520.

Flange 527 is formed in a position which is slightly lower than an upperend portion of pole 526, for example, by an amount corresponding to thethickness of the body of frame 525. Flange 527 has a little biggerdiameter than the trunk of pole 526.

Thus, since poles 526 are provided with flanges 527, poles 526 areattached in a manner that poles 526 are press-fitted into press-fittingholes 522 until flanges 527 move from the inside surface of frame 525and come into contact with a top panel of the body of frame 525.Thereby, a distance from the top panel of the body of frame 525 to alower end portion of pole 526 can be easily managed, and the vibrationgenerator can be easily assembled with high precision.

In the second embodiment, the hole provided in the pillar body of theholder may be a closed-end hole. In this case, it may be constituted sothat the length of the pole formed in the frame may be reduced. Thus,when each hole is a cylinder-like closed-end hole, the holder can beeasily molded. That is, resin easily surrounds the entire surface of thepillar body at the time of molding the holder. Therefore, so-calledsurrounding leakage of resin can be prevented, and thus the holder canbe easily molded. In particular, by providing a gate for allowing resinto flow out therethrough in a position near each pillar body, thiseffect can be more certainly obtained.

Others

The vibration generator may be constituted by suitably combiningfeatures in each embodiment or and its modifications described above.For example, in the vibration generator according to the secondembodiment, a double-sided substrate such as a glass epoxy substrateused in the first embodiment may be used instead of the flexible printedcircuit board. When using a double-sided substrate in this way, themanufacturing cost of the vibration generator can be reduced.

In the second embodiment described above, the notch portion of thebottom plate may be provided with a round-chamfered portion. Theround-chamfered portion may be provided in an edge portion which isformed when the notch portion is formed, for example. Therefore,although the substrate which is an FPC is bent in the notch portion,stress is unlikely to be applied to the substrate and breakage of thesubstrate, or the like can be more certainly prevented.

A frame may not be limited to iron but may be made of other materials.For example, it may be a resin body which is formed separately from aholder. The frame may not be provided with an upper surface and a bottomsurface and may surround the periphery of the holder when viewed fromabove. The frame may be a square when viewed from above.

The circuit board may not be needed. The bottom plate may not cover thewhole surface of the bottom of the frame but may be arranged at aportion of the bottom of the frame.

The number of protruding portions provided for the yoke may be 4, or maybe an odd number. The surface of the protruding portion is limited toneither a spherical surface nor a curved surface. The above effects canbe acquired when the protruding portion is formed such that a portion ofa limited area of the protrusion comes into contact with the inside ofthe frame.

The number of pillar bodies and the number of arms may be two or more.The pillar body may not be a cylindrical shape but may be a polygonalprism shape. The holder may not be an integrally formed body, but may bea body in which a plurality of members are assembled.

The attachment structure of the holder to the frame is not limited tothe structure in which two claws engage the pillar body or the structurein which each pole fits the hole of the pillar body. In the attachmentstructure of the holder to the frame, the fixed unit having anothershape on the holder side may engage engaging unit formed in the frame.For example, a hole-shape engaging unit is formed in the frame, and theprojection on the holder side may be fitted in the engaging unit toattach the holder to the frame.

The holder is not limited to one that formed by single-color molding.For example, the pillar body, the retention unit, and the arm may beintegrally molded by the two-color molding using different materials.

The attachment structure of the vibrator to the holder, namely, theattachment structure of the magnet and the yoke to the holder is notlimited to the insert molding. For example, the magnet and the yoke,which are joined to each other by the welding, may be assembled in andbonded to the integrally-molded holder in a process different from theprocess of molding the holder. Alternatively, the holder and the yokemay be integrally molded and then the magnet may be attached to theyoke.

The attachment structure for attaching the vibrator to the holder, i.e.,the attachment structure for attaching the magnet and yoke to the holderis not limited to an article prepared through insert molding. Forexample, the attachment structure may be a structure obtained byincorporating the magnet and yoke which are mutually joined throughwelding or the like into the integrally-molded holder in a processdifferent from a molding process of the holder, and then bonding themeach other. Alternatively, the holder and yoke may be integrally formedand after that the magnet may be attached to the yoke.

The weight may be arranged in the center portion of the magnet, etc. Theweight may be arranged in a portion of the magnet which does not greatlyaffect generation of force for moving the vibrator. Thereby, thevibration generator which enables miniaturization of the vibrator andcan generate a big vibration force can be obtained.

The vibration generator which can drive a vibrator may be constituted byattaching the coil to the main substrate of an apparatus using avibration, etc., and attaching the frame, to which the holder isattached, to the main substrate which is mounted with coil already. Inother words, the vibration generator may be constituted by using thecoil mounted on the substrate of other apparatus.

The configuration of the above holder is not limited to that of theholder for the vibration generator described above, but can be widelyapplied. That is, the holder is configured such that a movable unit (aportion serving as the vibrator in the above embodiment), in which themagnet is provided, can be displaced via the arm with respect to aportion supported by the frame. Such a holder can be used for anactuator driven using magnetism, an apparatus which suitably displaces amoving unit in a predetermined direction, and other various types ofapparatuses. When the holder is configured to have the same structure,the same effect as above can be obtained even in other apparatusesdifferent from the vibration generator. For example, when the yokeportion of the holder is provided with the protruding portion, it ispossible to restrict the portion where the movable unit and the framecan come into contact with each other, and thus the apparatus can beproperly operated.

The vibration generator is not limited to a small one which is describedabove. Even when the vibration generator is configured in a large sizewith the same structure, the same effect as above can be obtained.

According to the embodiment described above, the arm is connected to aportion of the vibrator retention unit, at which the protrusion isarranged, and the vibrator-mounted holder is attached to the chassis ina state where the arm is extended from a natural state. Therefore, avibrator-mounted holder and a vibration generator, which can be easilyassembled, can be manufactured at low cost, and have high reliability,can be provided.

It should be understood that the embodiments described above areillustrative and non-restrictive in every respect. The scope of thepresent invention is defined by the terms of the claims, rather than thedescription above, and is intended to include any modifications withinthe scope and meaning equivalent to the terms of the claims.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the scopeof the present invention being interpreted by the terms of the appendedclaims.

What is claimed is:
 1. A vibration generator comprising: a chassis; abottom plate fixed to the chassis; a vibrator including a yoke and amagnet connected to the yoke; a plate-like coil arranged at the bottomplate; an plurality of arms supporting displaceably the vibrator in adirection parallel with respect to the plate-like coil; and a vibratorretention unit coupling the vibrator and the plurality of arms, whereinthe magnet faces the plate-like coil in a direction of a winding axis ofthe plate-like coil, the magnet is arranged between end portions of theyoke in the parallel direction, the yoke includes a projecting portion,an end portion of the projecting, portion extending from the yoke towardthe bottom plate, and the projecting portion is fitted into a recessedportion of the vibrator retention unit between the plurality of arms ina longitudinal direction of the arms.
 2. The vibration generatoraccording to claim 1, wherein the vibrator retention unit and theprojecting portion of the yoke are formed integrally.
 3. The vibrationgenerator according to claim 1, wherein the vibrator retention unitmoves laterally.
 4. The vibration generator according to claim 1,wherein the recessed portion includes a surface facing the yoke in adirection from the yoke toward the plate-like coil, and the recessedportion is recessed from the surface in a projecting direction of theprojecting portion.
 5. The vibration generator according to claim 1,wherein a side edge portion of the yoke includes the one end portion andis bent at about 90°.